std::system_category
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Defined in header
<system_error>
const std::error_category & system_category() noexcept;
(since C++11)
Obtains a reference to the static error category object for errors reported by the operating system. The object is required to override the virtual function std::error_category::name() to return a pointer to the string "system". It is also required to override the virtual function std::error_category::default_error_condition() to map the error codes that match POSIX errno values to std::generic_category .
Contents
[edit] Parameters
(none)
[edit] Return value
A reference to the static object of unspecified runtime type, derived from std::error_category .
[edit] Notes
On Windows, system_category() typically maps some Windows error codes to POSIX ones. On POSIX, system_category() tends to be equivalent to std::generic_category() except for the name.
[edit] Example
Run this code
#include <iomanip> #include <iostream> #include <string> #include <system_error> int main() { for (int const code : {EDOM, 10001}) { const std::error_condition econd = std::system_category().default_error_condition(code); std::cout << "Category: " << econd.category().name() << '\n' << "Value: " << econd.value() << '\n' << "Message: " << econd.message() << "\n\n"; } }
Possible output:
Category: generic Value: 33 Message: Numerical argument out of domain Category: system Value: 10001 Message: Unknown error 10001
[edit] See also
(C++11)
(class) [edit]